Contact arc replication device

ABSTRACT

A device for measuring heat and pressure characteristics of a fusing contact arc or nip formed between heat and pressure fusing rolls for fusing powder images onto a copy sheet. A toner powder pattern is formed and fused on a silicone rubber layer which is supported by a sheet of paper. A second sheet of paper is placed on overlying position with the toner pattern of the device. The device and strip are positioned between the opened nip of heat and pressure fusing rolls which are then closed for a predetermined time. Upon separation of the rolls the device and sheet of paper are removed and stripped apart. A portion of toner powder pattern is offset from silicone rubber layer onto the sheet of paper indicating immediately heat and pressure characteristics of the fusing nip.

United States Patent Thettu Dec. 16, 1975 CONTACT ARC REPLICATION DEVICE Primary ExaminerS. Clement Swisher [75] Inventor: Raghulinga R. Thettu, Webster, Assistant Emmmer Dems Corr N.Y. [57] ABSTRACT [73] Asslgnee: g Corporanon Stamford A device for measuring heat and pressure characte ristics of a fusing contact arc or nip formed between heat [22] Filed: Dec. 12, 1974 and pressure fusing rolls for fusing powder images onto a copy sheet. A toner powder pattern is formed [21] Appl 532083 and fused on a silicone rubber layer which is supported by a sheet of paper. A second sheet of paper is [52] us. Cl 73/432 R placed on overlying position with the toner pattern of [51] Int. Cl. G01D 21/00 the device The device and strip are positioned [58] Field of Search 73/432 R, 159, 339; tween the Opened p of heat and pressure fusing rolls 432/227, 228, 229, 230, 59, 60; which are then closed for a predetermined time. Upon 219/106}; 427/413 separation of the rolls the device and sheet of paper are removed and stripped apart. A portion of toner [56] References Cited powder pattern is offset from silicone rubber layer UNITED STATES PATENTS onto the sheet of paper indicating immediately heat 3 669 707 6/1972 Dohnelly 432/60 and pressure characteristics of the fusing nip. 3,861,219 l/l975 Hendrickson 73/432 R 6 Claims, 7 Drawing Figures US met Dec. 16, 1975 Sheet 1 of2 3,926,058

US. Patent Dec.16, 1975 Sheet20f2 3,926,058

FIG. 20 FIG. 2b FIG. 2a

FIG. 4 FIG. 5

CONTACT ARC REPLICATION DEVICE This invention relates to a device for measuring heat .and pressure characteristics of a fusing apparatus for use with an electrostatic reproduction system to facilitate obtaining high quality copies.

It has been recognized that one of the preferred ways for fusing a powder image to a substrate is to bring the powder into direct contact with a hot surface, such as a heated roller. The roller surface may be dry, i.e., no application of a liquid release agent to the surface of that roller as described, for example, in U.S. Pat. Nos. 3,498,596, 3,539,161, and 3,666,247. Alternatively, the fuser roll surface may be melted with a release agent such as silicone oil as described in U.S. Pat. Nos. 3,268,351 and 3,256,002.

It has been found that the measurement of the pressure and temperature in the contact arc or nip of the rolls is desirable from the standpoint of adjusting the nip to obtain high quality fixing of copy sheets. Therefore, the ease with which these parameters can be immediately ascertained under varying conditions can be extremely advantageous in the set up of a machine in the minimum time.

The present invention is for a method and device for rapidly ascertaining the pressure and temperature level of the nip formed by heat and pressure fusing rolls used in reproduction machines and is particularly an improvement over copending application Ser. No. 370,182 now U.S. Pat. No. 3,861,219 commonly assigned with the instant application. This is accomplished generally speaking by offsetting a portion of a toner pattern from a sheet onto another sheet for immediate analysis and eliminating any possibility of bonding the two sheets together.

It is therefore the principle object of the present invention to improve heated pressure fusing roll devices.

It is a further object of the present invention to facilitate the measurement of pressure and heat levels in the nip of fusing rolls.

It is a further object of the present invention to improve significantly the quality of fixes produced by heated pressure fusing rolls.

It is a further object of the present invention to detect wear and/or damage in the construction of heated and pressure fusing rolls.

These as well as other objects of the invention and further features thereof will be better understood upon reference to the following detailed description of the invention to be read in connection with the accompanying drawings wherein:

FIG. 1 illustrates schematically a xerographic reproducing apparatus incorporating a heated pressure fuser roll apparatus having a nip of the type measured in accordance with the present invention:

FIGS. 2a c are side views of the fusing rolls illustrating the nip measurement steps in sequence;

FIG. 3 is a perspective view of the contact arc replication device according to the invention;

FIG. 4 is an enlarged portion of the device bearing a toner pattern indicating heat and pressure characteristics of the nip according to the invention; and

FIG. 5 is a view similar to FIG. 3 illustrating the corresponding offset toner pattern onto another member measuring heat and pressure characteristics of the nip.

Referring now to the drawings, there is shown in FIG. 1 an automatic xerographic reproducing machine incorporating heat and pressure fusing rolls having a nip measured according to the invention. The automatic xerographic reproducing machine includes a xerographic plate or surface 10 formed in the shape of a drum. The plate has a photoconductive layer or light receiving surface on a conductive backing journaled in a frame to rotate in the direction indicated by the arrow. The rotation will cause the plate surface to sequentially pass a series of xerographic processing stations. For the purpose of the present disclosure the several xerographic processing stations in the path of movement of the plate surface may be described functionally as follows:

A charging station A, at which a uniform electrostatic charge is deposited on the photoconductive plate;

An exposure station B, at which light or a radiation pattern of copies to be reproduced is projected onto the plate surface to dissipate the charge in the exposed areas thereof to thereby form a latent electrostatic image of the copy to be reproduced.

A developing station C, at which xerographic dev eloping material, including toner particles having an electrostatic charge opposite that of the latent electrostatic image, is cascaded over the latent electrostatic image to form a toner powder image in configuration of the copy being reproduced;

A transfer station D at which the toner powder image is electrostatically transferred from the plate surface to a transfer material of a support surface mode of pap er;

A drum cleaning and discharge station E at which the plate surface is brushed to remove residual toner particles remaining thereon after image transfer and at which the plate is exposed to a relatively bright light source to effect substantially complete discharge of any residual electrostatic charge remaining thereon, and

A fusing station F at which the toner powder image is affixed to the paper support material by fusing rolls 1 03 and which apply heat and pressure at a nip as will be described hereinafter.

The description of the xerographic process is considered sufficient for an understanding of the instant invention. Further details may be had by reference to U.S. Pat. No. 3,578,859 filed July 3, 1969 commonly assigned herewith.

The quality of the copies produced by the machine is greatly affected by the heat and pressure fusing characteristics at the nip formed fuser roll 103 and pressure roll 105. The fusing rolls may be wetted or dry as described above. In either case the nip pressure and heat 5 are critical in obtaining high quality fusing. For a typical dry system the fuser or heated roll 103 comprises a rotating member having an elastic compressible coating 132 made of silicone rubber or any suitable heat resistant compressible material as described, for example, in the aforementioned patents. The rotating member 130 may be internally heated by a heat source 134 as described in U.S. Pat. No. 3,666,247 or externally heated as described in U.S. Pat. Nos. 3,498,596

and 3,539,161. The pressure on back-up roll 105 comprises a rotating member which is covered with an elastic layer 142. When the two rolls 103 and 105 are engaged the applied load deforms the rubber in the pressure roll to provide the nip with a finite width. The copy sheet electrostatically bearing the toner images on the underside is brought into contact with the nip of the rolls with the toner image contacting the fuser roll 1 03. For a given temperature of the fuser roll, the fusing rate will depend upon the contact arc length of the support material against the dwell time, i.e., the time the toner images remain between the fuser roll 16 and the backup roll 18. Dwell time can be varied either by changing the surface velocity of the rolls or by varying the contact arc length and holding the speed of the roll the same. Contact arc length depends on the softness of the rubber on back-up roll 105 and on the amount of pressure between the rolls 103 and 105. The mechanism for driving the rolls and for lowering and raising the rolls into contact can be accomplished by any suitable means as that described, for example, in U.S. Pat. No. 3,291,466 or by a suitable mechanical camming device. The subject invention is concerned with the immediate determination of the heat and pressure characteristics of the contact arc or nip.

Referring specifically to FIGS. 2a c there is shown in sequence the steps of measuring the heat and pressure characteristics of the contact arc or nip formed by the fusing rollers. A measurement device 200 comprises a sheet of paper 201 which is covered uniformly with a layer 205 of silicone rubber material on one side thereof. Layer 205 has a minimum thickness of about 0.0002 inches and can be any suitable silicone rubber as for example RTVl 12, a tradename of General Electric Company. Covering layer 205 is a layer of toner material. A half toner pattern is very good for this purpose as best shown in FIG. 3. The toner material is applied electrostatically and fused to the silicone rubber layer in any suitable manner as by radiant heating material.

A sheet of paper 210 which is unmarked is positioned in overlying relationship with device 200. Device 200 and sheet 210 are inserted between the fusing rollers 103 and 105 while the rollers are separated as in FIG. 20. Next the fusing rollers are closed to form an operating nip for a predetermined time as in FIG. 2b. Preferably, this time period ranges from about the shortest dwell time of about 0.2 seconds time depending upon melting point, viscosity, roll temperature and sheet material to any maximum time depending upon paper decoloration. It will be appreciated that any suitable high temperature film material can be used for sheets 201 and 210 in place of paper. Other suitable materials are high temperature nylons or polyimide films.

Any suitable pigmented or dyed electroscopic toner material may be employed with the carriers of this invention. Typical toner materials include: gum copal; gum sandarac; rosin; cumaromeidene resin; asphaltum; phenol formaldehyde resins, rosin modified phenol formaldehyde resins; epoxy resins; polyethylene resins; polyester resins and mixtures thereof. The particular toner material to be employed usually depends upon the separation of the toner particles from the carrier beads in the triboelectric series and whether a negatively or positively charged image is to be developed. Among the patents describing electroscopic toner compositions are U.S. Pat.- Nos. 2,659,670 to Copley; 2,753,308 to Landrigan; 3,079,342 to Insalaco; Re- Issue 24,136 to Carlson, and 2,788,288 to Rheinfrank et al. These toners generally have an average particle diameter between about 1 and 30 microns. A toner comprising a styreneN-butyl methacrylate copolymer, polyvinylbutyral and carbon black produced by the method disclosed by M. A. Insalaco in Example I of U.S. Pat. No. 3,079,342 is preferred because of its excellent triboelectric qualities and its deep black color.

In the next step the fusing rollers are separated from each other to an inoperative position. The device 200 and sheet 210 are removed and separated whereupon a portion 220 of the toner pattern 215 in the vicinity of the nip is offset from device 200 onto sheet 210 as best shown in FIGS. 4 and 5.

It will be appreciated that the width of the offset toner portion 220 can be used to determine the fusing quality of the fuser rollers. Thus, if there is too much pressure there will be an increase over the standard nip width normally offset for the machine operating conditions. On the other hand, if there is insufficient pressure in the nip, the width will be decreased from the standard. Also the density of the nip width offset is useful to determine the temperature level of the nip. More specifically, if there is insufficient heat at the fusing nip there is poor transfer of offset portion 220 to sheet 210. On the other hand if the temperature is elevated beyond a standard temperature range the sheet 210 will become discolored or scorched.

It will be further appreciated that by observing the device 200 and sheet 210 that the toner pattern 215 and offset portion 220 in FIGS. 4 and 5 serve to determine immediately the heat and pressure levels of the nip formed by the fusing rolls. It will be noted that if the transfer of offset portion 220 is uniform the density and a width meeting standard specifications, then the fix level of the fusing apparatus is acceptable. With this in mind the pressure and/or temperature of the nip can be adjusted and the tests easily repeated until the desired operating conditions are obtained. Also the image will not bleed or fade and is resistant to fluids and therefore is a permanent record. Moreover, since the toner material is the same as is used in the machine processor during operating conditions, the toner material serves as a measurement reference as well.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. A device for measuring heat and pressure characteristics of a nip between pressure heated fusing rolls comprising:

a first sheet of support material,

a uniform layer of silicone rubber bonded to said support material, and

a layer of toner material coated on said silicone rubber whereby upon positioning a second sheet of unmarked support material in overlying contact with said toner layer and insertion of the sheets between pressure heated fusing rolls for a predetermined time and separation of the sheets, a portion of the toner pattern is offset from said silicone rubber layer onto said second sheet immediately indicating heat and pressure characteristics of the nip.

2. A device according to claim 1 wherein the minimum thickness of the silicone rubber is about .0002 inches.

3. A device according to claim 1 wherein at least one of said first and second sheets is made of paper.

4. A device according to claim I wherein at least one of said first and second sheets is made of a high temperature nylon.

3 ,9 26,05 8 5 i 6 5. A device according to claim 1 wherein at least one material layer m *Predetermmed pattern formed by electrosta'nc processing. of said first and second sheets lS made of a polyimlde film.

6. A device according to claim 1 wherein said toner 

1. A DEVICE FOR MEASURING HEAT AND PRESSURE CHARACTERISTICS OF A NIP BETWEEN PRESSURE HEATED FUSING ROLLS COMPRISING: A FIRST SHEET OF SUPPORT MATERIAL, A UNIFORM LAYER OF SILICONE RUBBER BONDED TO SAID SUPPORT MATERIAL, AND A LAYER OF TONER MATERIAL COATED ON SAID SILICONE RUBBER WHEREBY UPON POSITIONING A SECOND SHEET OF UNMARKERD SUPPORT MATERIAL IN OVERLYING CONTACT WITH SAID TONER LAYER AND INSERTION OF THE SHEET BETWEEN PRESSURE HEATED FUSING ROLLS FOR A PREDETERMINED TIME AND SEPARATION OF THE SHEETS, A PORTION OF THE TONER PATTERN IS OFFSET FROM SAID SILICONE RUBBER LAYER ONTO SAID SECOND SHEET IMMEDIATELY INDICATING HEAT AND PRESSURE CHARACTERISTICS OF THE NIP.
 2. A device according to claim 1 wherein the minimum thickness of the silicone rubber is about .0002 inches.
 3. A device according to claim 1 wherein at least one of said first and second sheets is made of paper.
 4. A device according to claim 1 wherein at least one of said first and second sheets is made of a high temperature nylon.
 5. A device according to claim 1 wherein at least one of said first and second sheets is made of a polyimide film.
 6. A device according to claim 1 wherein said toner material layer is in a predetermined pattern formed by electrostatic processing. 